Recovery of sulphur



Juy M9 1933. R. F. BACON Er AL 1,917,788

RECOVERY OF SULPHUR Filed Feb. 25, 1930 Rocco FNELLI ATTORNEYS Patented July 11, 1933 UNTD ares PATENT; oFFicE *nari/rerun F. Bacon, or BiioNXvrLLn, Ann Rocco raiviiLLr, or NEW ROCHELLE, NEW

YORK; SAID FANELL ASSIGNGR T0 SAID BACON Vmioovriiw or sULrHun Application led February 25, 10930. Serial No. 431,133.

This invention relates to the recovery of sulphur and has for an object the provision of an improved process for recovering sulphur from heavy ymetal sulphide ores. More par'- ticularly, the invention contemplates the p rovision of an improved process for recovering sulphur from materials containing. one or more sulphides of iron. The invention f urther contemplates the provision ofan 1mproved process for treating heavy inetalsul# phide ores1 such, for example, as ore con taining sulphides of iron, copper and nichel.

he processof thepresent invention involves the treatment or ore or other metallurgical raw materials or productsvcontainpyrites or other sulphides of iron, alone or in combination with sulphides of other heavy metals, such, for example, as copper and niclrel with chlorine for the purpose. of obtaining free sulphur and/or separating i iron from the mass of material undergoing treatment.

ln carrying out ay process in accordance with the present invention, a quantity of the material to be treated is subjected to the action ofV chlorine under suoli conditions that ferrous chloride and free sulphur are formed. The process is so conducted that the sulphur produced is vaporized, leaving a residue containing the ferrous chloride together with chlorides of other heavy metals such as copper and iclrel when the sulphides of such metals' are present in the material being treated. The residue containing ferrous chloride is subjectedfto the action of air and steam to produce hydrogen chloride. The hydrogen chloride produced is dried'and subielcted to the action of air in the presence of a suitable catalyst to produce free chlorine which is returned tothe process.

The invention will beV better understood from a consideration of the accompanying fiowsheet Vand the following description of the application of the process to the treatment of ore containing sulphides ofcopper, nickel and iron. i

rlhe ore to betreated is subjected to the action of chlorine under suchy conditions that ferrous chloride and free sulphur are produced. The operation is so conducted that the sulphur produced is vaporized, leaving a residue containing the ferrous chloride together with the chlorides of copper and nichel. The sulphur may be swept from the reaction chamber by means of inert gases inl troduced withtheclilorine or auteniperature sufficiently high to vaporize the sulphur may be maintained and substantially pure chloine may be employed.

process may be employed for treating the sulphidesbearing material. .The chlorinerecovered `is mixed with inert gases. When the mixture of gases is vemployed the chlorinating operationinay bev conducted at a teni# perature below the boiling pointfof sulphur, the inert gases serving to sweep the sulphur ,Chlorine which is` recovered during'a subsequent stage of` the elli from the reaction chamber.l The mixture yof gases may be employed to aid invaporizing the sulphur Vwhen the reaction chamber is maintained at a temperature above the boiling point of sulphur.

The ore is preferably introduced in a dry, finely divided condition into .the interior of a rotary reaction chamber having ore-charging meansat one end and vdischarging means at the other end, and which is so constructed l and operated that the ore is gradually movedy tained near the charging end of the reaction' chamber, and a temperature of about 300o C.v to 3509. isl maintained near the dis charge end of the reaction chamber. The chlorine in any desired concentration and y on at any desired temperature is introduced into ioo phur, ferrous chloride and the chlorides of copper and nickel. The admission of ore and chlorine is preferably so regulated that all of the sulphur liberated is vaporized as elemental sulphur, all of the chlorine admitted is consumed, and substantially all of the iron suphide is convert-ed to ferrous chloride. Any ferrie chloride which is produced in the reaction chamber will be vaporizcd and swept along with the incoming chlorineto meet the entering iron sulphide-bearing-material. The ferrie chloride will react with the sulphides to forni ferrous chloride and sulphur chloride. Sulphur chloride which is formed will also react with the heavy metal sulphides. The reaction between the sulphides and the chlorine is exothermic and the desired temperatures may be maintained bythe heat developed.

` Tliesulphur producedfis vaporized land separatedfroiii the heavy metal chlorides in the hottest portion of the reaction chambei', and the residue'containing the heavy metal chlorides is discharged from the reaction Vchamber at a temperature of about 300o C. to 3500 C.

he hot residue containing ferrous cliloride and the chlorides of nickel and copper is c treated with steam-in order to produce hydrogen chloride and oxides of the metals by of the iron. The air and steam are preheatedl in order to assist in maintaining the mass at the desired reaction temperature.

' The hydrolysis will take place at normal atmospheric temperatures, but the rate of reaction is too vslow for practical purposes. Higher temperatures not only increase the speed of the hydrolysis but also assist in the air oxidation which takes place. The treatnient of the ferrous cliloride-bearing material'with air and steam may be carried out satisfactorily at a temperature of from 4400 C. to 600o C. Ordinarily, a reaction temperature of about 500o C. is entirely satisfactory.

The treatment of the ferrous chloridee bearing material with air and steam may be A ing end and the resulting heavy metal oxides and hydrogen chloride are removed from the reaction chamber vat the discharge end. The oxides and hydrogen chloride are preferably removed through separate discharge outlets. If the hydrogen chloride gas leaving the chamber carries considerable amounts of entrained particles of oxides it may be desirable to provide a settling chainber into which the oxides and hydrogen chloride may be intreduced from the reaction chamber. Such a chamber should be maintained at a sufiicienlly high temperature to prevent the reverse reaction.

Means such, for example, as porcelain balls or other large pieces of inert materials are provided within the reaction chamber to prevent the chlorides from adhering to the walls of the chamber. Such means aid in stirring and grinding the chlorides and oxides as they pass through the reaction chamber.

The gases issuing from the reaction chamb'e'r contain hydrogen chloride and water vapor and they are passed through a suitable drying' apparatus such, for example, as a packed tower having sulpliuric acid trickling therethrough to separate the water vapor and produce dry hydrogen chloride.

TheV dry hydrogen chloride is introduced into a' catalytic reaction chamber with one to 'seven times its volume ofrair, depending on the concentration of the hydrogen chloride' available. The air is preheated to a temperature above 4200 C. and preferably to a temperature between 5:20 and 530o C. If desired, the hydrogen chloride may also be preheated.

The catalytic reaction chamber preferably consists of a. tower, or a series of communicating towers packed with a material having a very large surface per unit of volume such, for example, as p'umice, brick, cinders and the like. The packing material should be of suoli a nature that it will be inert to the reagents and the products ofthe reaction. The packing material is covered or impregnated with the catalyst which may be one or more chlorides or sulphates of metals such, for example, as copper and nickel. The salts may be applied as suoli directly to the packing material or they may be formed in place as, for example, by the action of hydrogen chloride on copper oxide which is distributed throughout the mass. Means are provided for renewing the catalytic mass as its etliciency becomes reduced. F or this purpose two towers or two series of communicating` towers which may be used alternately are preferably provided.

A portion of the massof oxides resulting from the treatment of the ferrous chloridebearing material with steam and air may be utilized as a catalytic agent for promoting the reaction between the hydrogen chloride and oxygen.

The apparatus is preferably so constructed that the mass of catalyst-bearing material may be niaintained'at a temperature of from 370 C. to 400o C. The reaction between the hydrogen chloride and ,the oxygen of the air is exorthermic and it may be socontrolled consist of a mixture of hydrogen chloride,l

Water vapor and chlorine.-

In vie-v of the fact that the reaction does not readily proceed to completion, it may be desirable to retreat the issuing gases by subjecting them to a ldrying operation to remove vthe Water vapor and subsequently passing them through a second reaction chamber. rllhis procedure may be repeated tivo or three or more times if desired. ln carrying out the reaction between hydrogen chloride and the oxygen of air it is advisable to carefully control the proportions of air and hydrogenr chloride utilized in order to avoid excessive dilution of the resulting chlorine gas.

rlhe gases containing hydrogen chloride` and chlorine are Washed With Water to separate the chlorine and hydrogen chloride.' Theresulting solution of hydrogen chloride in Water may be treated in any suitable man'- ner to recover the hydrogen chloride. The chlorine recovered is dried and utilizedl for treating additional. iron sulphide-bearing material.

The process may be conducted continuously. A source of supply of fresh chlorine is provided to compensate for chlorine losses due to leakage and other causes. The fresh chlorine may be supplied as free chlorine or hydrogen chloride, and the choice Will depend upon the relative costs.

TvVeclaim:

l. The method of treating iron sulphidebearing material containing sulphides of one or more other heavy metals Which comprises subjecting the material to the action of chlorine under such conditions that elemental sulphur and a dry, substantially non-fused product containing ferrous chloride and chlorides of such other heavy metals as may be present in the material are formed and the sulphur is vaporized, subjecting the combined chloride product directly to the action of air and steam to produce simultaneously hydrogen chloride and oxides of the heavy metals, treating the hydrogen chloride to recover chlorine, and returning the chlorine thus recovered to the process. n

2. The method of treating iron sulphidebearing material containing sulphides of oney or more other heavy metals Which comprises subjecting the material to the action of chlorine under such conditions that elemental sulphur and a dry, substantially non-fused product containing ferrous chloride and chlorides of such other heavy metals as may be present in the material are formed and the sulphur is vaporized, .subjecting the combined chloride product directly to the act-ion of air and steam to produce simultaneously hydrogen chloride and oxides of the heavy metals, subjecting the hydrogen chloride to the action of air in the presence of a catalyst to recover chlorine, and returning the chlorine thus recovered to the process.

3. The method of `treating iron sulphidebearing material containing sulphides of one or more other heavy metals which comprises subjecting the material to the action of chlorine under such conditions that elemental sulphur and a dry, substantially non-fused K product containing ferrous chloride and chlorides of such other heavy metals as may be present in the material are formed and the sulphur is vaporized, subjecting the combined chloride product directly to the action of air and steam at a temperature of about 40 C.. to 600O C. to produce simultaneously hydrogen kChloride and oxides of heavy metals, treating the hydrogen chloride to recover chlorine, and returning the chlorine thus recovered to the process..

4. The method of treating iron sulphideioo bearing material containing sulphides of one or more other heavy metals which comprises subjecting the material to the action of chlorine under such conditions that elementaly sulphur and a dry, substantially non-fused product containing ferrous chloride and chlorides of such other heavy metals as may be present m the material are formed and the sulphur. is vapOriZed, subjecting the combnied chloride product directly to the action ius Y of air and steam at a temperature of about 4400 C. to 6000 C. to produce simultaneously hydrogen chloride and oxides of the heavy metals, subjecting the hydrogen chloride to the action of'aii in the presence of a catalyst to recover chlorine, and returninfr the chlorine thus recovered to the processa In testimony whereof We aliix our signatures. D

RAYMOND F. BACON. ROCCO FANELLI. 

